Pros and cons of different timber frame wall build up

[AliG]

I am using my time working from home to try and finalise the plans for my parents' house so that we can hopefully get started asap once life gets back to normal.

 

I have spoken to a couple of timber frame companies and I also chatted a bit to @Jeremy Harris re his MBC frame.

 

I am seeing frames with 140mm, 184 and 235mm studs as well as the 300mm twin wall systems as used by MBC and some others.

 

We have drawn up the plans with a 400mm wall thickness, and have a width restriction.

 

So we could use a 300mm frame plus render board, or we could use a 140mm frame plus PIR and rockwool or a thicker frame from some suppliers.

 

Having run the heat input calculations, the wall u-values don't make much difference. The house has a lot of glass and I plan to have around 0.1 on the floor and roof. Thus whether the walls are 0.11 or 0.13 or 0.15 hardly makes any difference to heating costs.

 

I am thinking more about other things such as noise, sturdiness etc. Jeremy has said how quiet his house is for example. My last house was timber frame plus rendered blockwork, but I think it was only a standard 90mm stud as mainly used 20 years ago. The house was quite noisy and creaked in strong winds.

 

So would I notice a big difference between different stud thicknesses and different cladding systems or is it more about the detailing and the sealing of all the gaps.

 

Also looking at the quotes as they come in, we could end up with quite a lot of steel, should I be worried about the cold bridging or can it be well insulated within the frame?

 

One more question (copyright Columbo) - Most of the timber frame systems seem to allow for a 35mm batten then plasterboard to create a service void. If we avoid pipework and sockets on some outside walls to remove the void would we notice any other diffference? Does the void help to reduce noise transfer through the wall for example?

 

Edited April 8, 2020 by AliG

[ProDave]

Ours is a 195mm frame (filled with Frametherm 35) and 100mm wood fibre board on the outside then render. The house with 3g Rationel windows is extremely quiet.

 

It does not creak or groan in strong wind,  No steelwork in ours. The SE specified two layers of OSB on the frame as the racking layer with staggered joints.

 

Same 100mm wood fibre used as the roof sarking and same frametherm insulation making a warm roof supported on a ridge beam.

 

We have 25mm service void,  that and 12mm plasterboard is a perfect fit for 35mm back boxes for the electrics.  15mm (soldered copper) pipework fits in the 25mm gap.  The utility room is the only place we have any 22mm pipes in the wall and that has a 45mm service void.

 

Our bathroom was tight on space, so the outside wall there has no pipes or cables and the plasterboard goes straight on the frame with no service void.  No difference in accoustics noticed.

[AliG]

Two layers of OSB must make a nice difference.

 

I am guessing that wider studs help also as they might be stiffer.

 

Of course not many people have the experience of different systems to compare maybe.

[ProDave]

Previous house was a cold roof with trusses.  That had a habit of making some loud creaks and cracks when the roof heated up on a warm day.

 

The NO1 thing I would say is make a warm roof with a ridge beam.  SO much easier to make air tight and so much better use of space.

[AliG]

Flat roof so I don’t have to worry about that. I am also thinking that might be a lot quieter anyway

[SteamyTea]

15 hours ago, AliG said:

Flat roof so I don’t have to worry about that. I am also thinking that might be a lot quieter anyway

How are you going to make it waterproof?

[AliG]

Part of the roof will be a sedum roof, under this and for the rest of the roof I would assume EPDM although nothing has been specified at the moment.

[AliG]

 

This thread actually has a lot of good info for my question.